A suspecting Khloe Kardashian had her philandering husband Lamar Odom tailed by a private investigator who uncovered evidence that he had cheated on his wife with up to FIVE mistresses, RadarOnline.com has been told.

“Khloe has not only photographic proof that Lamar cheated on her with at least five different women, but has copies of text messages between Lamar and the other women,” the insider revealed.

“She is a very smart woman and knew she had to get the proof because of the infidelity clause in their prenup.”

As a result, drug-troubled Odom could be forced to pay Khloe, the youngest of the three Kardashian daughters, a “very large lump sum of cash, or a very hefty spousal support” if the couple does end up divorcing, the source said.

Among the goodies the twosome share include a $500,000 Rolls Royce, a $140,000 Porsche Panamer and Khloe’s $850,000 engagement ring, which would all be divided should the day come.

Kardashian would keep their Tarzana, Calif., mansion in the event of a split.

Odom, 33, has been living at his apartment in Downtown Los Angeles over the past few weeks, having rejected three separate interventions from those close to him who desperately want him to seek help for his addictions.